VMAgent: disabling HPA does not delete the HPA

Removing spec.hpa from a VMAgent leaves its HPA active.

Steps to reproduce

Create a VMAgent with HPA:

apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
  name: test
spec:
  remoteWrite:
    - url: http://example.invalid/api/v1/write
  resources:
    requests:
      cpu: 100m
  hpa:
    minReplicas: 1
    maxReplicas: 3
    metrics:
      - type: Resource
        resource:
          name: cpu
          target:
            type: Utilization
            averageUtilization: 80

kubectl apply -n vm -f vmagent.yaml
kubectl get hpa -n vm test

Remove the HPA configuration:

kubectl patch vmagent -n vm test \
  --type=json \
  -p='[{"op":"remove","path":"/spec/hpa"}]'

sleep 5
kubectl get hpa -n vm test

Evidence

The HPA still exists:

NAME   REFERENCE      TARGETS         MINPODS   MAXPODS
test   VMAgent/test   <unknown>/80%   1         3